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Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 Times Cited Count:1 Percentile:24.67(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Anomalous radioisotope production for $$^{68}$$ZnO using polyethylene by accelerator neutrons

Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Shintaro; Minato, Futoshi; Kawabata, Masako*; Hatsukawa, Yuichi*; Hashimoto, Kazuyuki*; Watanabe, Satoshi*; Saeki, Hideya*; Motoishi, Shoji*

Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03

 Times Cited Count:2 Percentile:51.78(Physics, Multidisciplinary)

We found anomalously large yields of $$^{67}$$Ga, $$^{66}$$Ga, $$^{rm 69m}$$Zn and $$^{64}$$Cu by neutron irradiation on a $$^{68}$$ZnO sample in a polyethylene shield. Neutron beams are generated from the $$^{9}$$Be($$d,n$$) reaction for 50 MeV deuterons. The yields obtained were more than 20 times larger than those in the unshielded sample. On the other hand, the yields of $$^{67}$$Ga, $$^{66}$$Ga, $$^{rm 69m}$$Zn and $$^{64}$$Cu from a metallic $$^{68}$$Zn sample and the yields of $$^{67}$$Cu, $$^{65}$$Ni and $$^{65}$$Zn from the $$^{68}$$ZnO and $$^{68}$$Zn samples were almost insensitive to the shield conditions. This finding would provide us a unique capability of accelerator neutrons to simultaneously produce a large amount of several radioisotopes, including proton induced reaction products, by using a single sample. The experimental data were compared with the yields estimated by using the Particle and Heavy Ion Transport code System and the result was discussed.

Journal Articles

Measurement and estimation of the $$^{99}$$Mo production yield by $$^{100}$$Mo($$n,2n$$)$$^{99}$$Mo

Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi*; Watanabe, Satoshi*; Saeki, Hideya*; Kawabata, Masako*; Hashimoto, Shintaro; Nagai, Yasuki*

Journal of the Physical Society of Japan, 86(11), p.114803_1 - 114803_6, 2017/11

 Times Cited Count:7 Percentile:59.82(Physics, Multidisciplinary)

We have measured the yield of $$^{99}$$Mo, the mother nuclide of $$^{99m}$$Tc used in nuclear diagnostic procedure. $$^{99}$$Mo was produced by $$^{100}$$Mo($$n$$,$$2n$$)$$^{99}$$Mo using neutrons with thermal energy up to about 40 MeV, provided by C($$d$$,$$n$$). The $$^{99}$$Mo yield agrees with an estimated yield with the use of the latest data of C($$d$$,$$n$$) and the evaluated cross section given in the JENDL. Based on this, a new calculation was carried out to produce $$^{99}$$Mo to seek for a good economical condition. Various conditions such as the $$^{100}$$MoO$$_{3}$$ sample mass, the distance between the carbon target and the sample, the radius of the deuteron beam, and the neutron irradiation time were considered. The calculated $$^{99}$$Mo yield indicates that about 30% of the $$^{99}$$Mo demand in Japan can be fulfilled with a single accelerator. The elusion of $$^{99m}$$Tc from the $$^{99}$$Mo twice per day would meet about 50% of the $$^{99}$$Mo demand.

Journal Articles

Superdeformation in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.

JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06

Journal Articles

Full-coherent free electron laser seeded by 13th- and 15th-order harmonics of near-infrared femtosecond laser pulses

Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08

 Times Cited Count:3 Percentile:21.46(Optics)

By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10$$^{2}$$ with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.

Journal Articles

Analysis of inclusive $$(d,xp)$$ reactions on nuclei from $$^9$$Be to $$^{238}$$U at 100 MeV

Ye, T.*; Hashimoto, Shintaro; Watanabe, Yukinobu*; Ogata, Kazuyuki*; Yahiro, Masanobu*

Physical Review C, 84(5), p.054606_1 - 054606_8, 2011/11

 Times Cited Count:20 Percentile:77.72(Physics, Nuclear)

Inclusive proton emission from deuteron-induced reactions on various nuclear targets at an incident energy of 100 MeV are analyzed using the CDCC theory for elastic breakup process and the Glauber model for neutron stripping process. Moreover, the phenomenological moving source model is used to estimate evaporation and pre-equilibrium components in inclusive $$(d,xp)$$ spectra. The calculation reproduces fairly well a prominent bump in experimental $$(d,xp)$$ spectra for light and medium nuclei at forward angles of less than 20$$^{circ}$$, whereas the calculation underestimates the bump component as target atomic number increases. The underestimation is likely to be attributed to the fact that the eikonal approximation used in the Glauber model becomes worse due to strong Coulomb interaction. It is shown that the Glauber model calculation for neutron stripping process leads to improvement of this discrepancy by substituting the eikonal phase shift for the quantum phase shift.

Journal Articles

Extreme ultraviolet free electron laser seeded with high-order harmonic of Ti:sapphore laser

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.

Optics Express (Internet), 19(1), p.317 - 324, 2011/01

 Times Cited Count:88 Percentile:96.89(Optics)

The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.

JAEA Reports

JFY 1995 Progress report of the development on the actinide recycle test reactor(ARTR)

Kasai, Shigeo; Tozawa, Katsuhiro; Akatsu, Minoru; Ogawa, Shinta; Watanabe, Ichiro; Hayafune, Hiroki; Naganuma, Masayuki; Ichimiya, Masakazu; Hayashi, Hideyuki; Mukaibou, Ryuichi

PNC TN9430 96-004, 152 Pages, 1996/07

PNC-TN9430-96-004.pdf:6.15MB

Authors are studying the Actinide Recycle Fast Breeder Reactor (named ARFBR in this paper), which contribute to the reduction of burdens to environments and to enhance the capability to prevent the nuclear proliferation as the entire nuclear recycle system (named Advanced Fuel Recycling FBR system (AFRFS) in this paper), and also investigating the ARTR for developing the ARFBR. The investigation of the ARTR consists of the design study of the ARTR and R&Ds of key technology existing in ARTR concept. The conceptual design study of the ARTR is planed to be conducted for 2 years from 1995 to 1996 as first stage. 1995's design study have been performed with drawing over all plant concept with supposing various tests in reactor and usage of reactor. Followings are distinctive feature of 1995's design study. (1)Maximum reactor power is 400MWt with about 1.6m diameter irradiation (burning) cores, which are designed to be operated up to 150GWd/t as average burn up. Maximum core diameter is about 2.5m for low power nuclear physics tests which are designed to be able to estimate characteristics of large scale core by using the test results. (2)Mixed oxide (MOX) and Mixed nitride (MN) core is designed respectively to be able to be used for static nuclear physics test, for nuclear and thermal transient test, and for full power irradiation or burning test. Each core is designed to terminate ATWS events passively, with using GEM for MOX core and with using spectral adjustment for MN core. (3)Fuel assembly is employed ductless type which is a promising candidate for the ARFBR. Sizing of a fuel assembly is determined in basis on MOX fuel design because MOX fuel pin length covers MN fuel pin which accommodates lesser FP gases because of its lower temperature. Fuel assembly is managed to be held by hydraulic force in case of freeing mechanical stopper by requirement of testability. (4)Reactor assembly is designed based on so called Head Access Loop Type Reactor. Main changes ...

Oral presentation

Analysis of inclusive $$(d,xn)$$ and $$(d,xp)$$ reactions for energies up to 100 MeV

Ye, T.*; Watanabe, Yukinobu*; Ogata, Kazuyuki*; Hashimoto, Shintaro; Yahiro, Masanobu*

no journal, , 

Oral presentation

Systematic analysis of (d,xn) and (d,xp) breakup reactions for energies up to 100 MeV

Watanabe, Yukinobu*; Ye, T.*; Hashimoto, Shintaro; Ogata, Kazuyuki*; Yahiro, Masanobu*

no journal, , 

no abstracts in English

Oral presentation

Calculation of heavy ion-induced DNA damage based on microdosimetric quantities

Watanabe, Ritsuko; Yokoya, Akinari; Hashimoto, Shintaro; Sato, Tatsuhiko

no journal, , 

The microscopic distribution of energy deposition is an essential factor to determine the relative biological effectiveness (RBE) of heavy ions. Although the linear energy transfer (LET) is the most generally used parameter for comparison of RBE, microdosimetric quantities as lineal energy (y) are considered to be more suitable parameter, as they reflects the ionization densities in microscopic sites. In this study, we focus on the evaluation of the number of DNA damage in relation to the microdosimetric quantities in the sites of sub-cellular sizes by Monte Carlo simulation. The numbers of double strand breaks (DSB), complex damages were calculated around the several mono-energetic ions. In the presentation, the number of DNA damage induced in the microscopic site correlated with the lineal energy and also the spatial distribution of the damages along the ion trajectories will be shown and discussed in terms of the cell-survival fraction models.

Oral presentation

Analysis of (d,n) reactions using a calculation code system for deuteron-induced reactions

Nakayama, Shinsuke*; Araki, Shohei*; Watanabe, Yukinobu*; Iwamoto, Osamu; Hashimoto, Shintaro; Ye, T.*; Ogata, Kazuyuki*

no journal, , 

A code system to calculate the cross sections for deuteron-induced reaction has been developed to create a deuteron nuclear data library that is important for the accelerator neutron sources. The (d,xn) reactions below 20 MeV that are important for the neutron source have been analyzed. It was found that the calculated results agree with the experimental data of the angular distribution at forward angles to the N-13 ground state by the proton stripping reactions for the deuteron induced reaction on C-12. The results of the analyses of the neutron yields for the C thick target will be reported.

Oral presentation

How many DNA damages are caused in whole body by radiation exposure ?

Hashimoto, Shintaro; Watanabe, Ritsuko; Sato, Tatsuhiko

no journal, , 

We have developed a model to estimate probabilities of cell survival by combining a mathematical model of dose distribution, which was obtained by the truck structure simulation, with PHITS. In this study, we performed the modeling of relation between dose distribution at micro-scale and the number of DNA damages, which were given by the analysis of the truck structure simulation. Then, a method to estimate the number of DNA damages at macro-scale was developed using PHITS with the relation. It is expected that an analysis of the radiation influence at the macro-scale with the new model clarifies the relation between DNA damages by radiation and the influence such as cancer causing. Furthermore, we will introduce the distribution of the DNA damages in human body irradiated by heavy ions.

Oral presentation

Adsorption study on PGM elements by AlHCF from nitric acid solution

Mishima, Ria; Tachioka, Sotaro*; Inaba, Yusuke*; Harigai, Miki*; Matsumura, Tatsuro; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

In Japan, the final disposal of high level liquid waste (HLLW) will be done after vitrification into borosilicate glass and then disposed into deep underground. In this vitrification process, there are some concerns. The first concern is precipitation of platinum group metals (PGMs) in the melter due to their low solubility into borosilicate glass. The second concern is the formation of yellow phase caused by Mo content. The final concern is the generation of huge number of vitrified glasses and the requirement of wide space needed for final disposal. Among many kinds of extractants and adsorbents for separation of such metal ions, metal hexacyanoferrate (HCFs) were reported to have an ability to adsorb PGMs. The objective of this study is to elucidate the adsorption behavior of aluminum hexacyanoferrate (AlHCF) for various metal ions and understand the relation between elution and adsorption. The effect of synthetic and workup conditions on PGM and Mo adsorption from simulated HLLW (sHLLW) was surveyed. Also, the relationship between adsorption of metal ions and elution of the AlHCF was studied. The synthesized AlHCF showed adsorption performance for PGMs and Mo in simulated HLLW. As a result of an adsorption test with a Pd single component solution to investigate the adsorption mechanism, the eluted element ratio was Fe:Al = 1:4 in the Pd adsorption test. However, the element ratio was Fe:Al = 3:4 in the original AlHCF. Therefore, it was suggested the existence of not only Pd adsorption, but also resorption and stabilization mechanisms.

Oral presentation

Development of cyano-group bridge-type coordination polymer with a high sorption characteristic of platinum-group elements for high quality and volume reduction of vitrified objects containing high-level radioactive nuclear wastes, 10; Platinum-group elements sorption studies of aluminum ferrocyanide

Mishima, Ria; Tachioka, Sotaro*; Inaba, Yusuke*; Harigai, Miki*; Matsumura, Tatsuro; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

In Japan, the final disposal of high level liquid waste (HLLW) will be done after vitrification into borosilicate glass and then disposed into deep underground. In this vitrification process, there are some concerns. The first concern is precipitation of platinum group metals (PGMs) in the melter due to their low solubility into borosilicate glass. The second concern is the formation of yellow phase caused by Mo content. The final concern is the generation of huge number of vitrified glasses and the requirement of wide space needed for final disposal. Among many kinds of extractants and adsorbents for separation of such metal ions, metal hexacyanoferrate (HCFs) were reported to have an ability to adsorb PGMs. The objective of this study is to elucidate the adsorption behavior of aluminum hexacyanoferrate (AlHCF) for various metal ions and understand the relation between elution and adsorption. The effect of synthetic and workup conditions on PGM and Mo adsorption from simulated HLLW (sHLLW) was surveyed. Also, the relationship between adsorption of metal ions and elution of the AlHCF was studied. The synthesized AlHCF showed adsorption performance for PGMs and Mo in simulated HLLW. As a result of an adsorption test with a Pd single component solution to investigate the adsorption mechanism, the eluted element ratio was Fe:Al = 1:4 in the Pd adsorption test. However, the element ratio was Fe:Al = 3:4 in the original AlHCF. Therefore, it was suggested the existence of not only Pd adsorption, but also resorption and stabilization mechanisms.

Oral presentation

Vacancy-type defects in garnet crystals revealed by gamma-ray-induced positron annihilation spectroscopy

Kitaura, Mamoru*; Fujimori, Kosuke*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

Positron annihilation spectroscopy is the only way to investigate the properties of cation vacancies because they are negatively charged. We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Oral presentation

Origin of phosphorescence in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ crystals revealed by gamma-ray induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This indicates that the Al/Ga vacancies disappear. This fact corresponds well with the suppression of the phosphorescence component and is an important result showing that the Mg co-doping is effective in suppressing the shallow electron capture center.

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